This is just simple Pythagorean’s theorem. a^2 + b^2 = c^2
Number 2:
5^2 + x^2 = 10^2
25 + x^2 = 100
x^2 = 75
x = sqrt 75 = 5*sqrt(3)
Number 3:
4^2 + x^2 = 7^2
16 + x^2 = 49
x^2 = 33
x = sqrt 33
On average, 2 will fall apart. We can tell this by making a proportion.
1/20 = x/40 ---> cross multiply
1*40 = 20*x ---> multiply
40 = 20x ----> divide by 20
2 = x
Answer: 90 + 4, third choice and 90 - -4, last choice
Her score is obviously higher when the mistake is fixed, adding the 4 points gives 94.
